The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Sand production from oil/gas bearing formations can create several problems including accumulation in surface facilities, wellbore collapse and erosion of equipment such as screens, safety valves, and tubulars etc. To control sand production, a gravel pack is typically placed in the annulus of the screen and the formation/casing. It is necessary to have a tight gravel pack that occupies the entire volume of the annulus without any voids. If voids are present, the gravel can shift and rearrange around the screen during production leading to a potential exposure of the screen to the formation sand. This could result in local erosion of the screen known as hot spot through which sand can enter the production tubing. In vertical and deviated wells (<600 from vertical), gravitational force assists in achieving a tight gravel pack. However, in highly deviated (>600, angle of repose) and horizontal wells, achieving a tight gravel pack is difficult as the sand settles out of the fluid before it is carried to the bottom of the annulus. Gravel packs are placed in wellbores between a screen and a formation face and/or casing to prevent formation sand from flowing into the wellbore and to improve wellbore and near-wellbore conductivity. The conductivity at the wellbore and near-wellbore is important because any damage in these locations significantly increases the pressure drop of fluid flow, thereby reducing the producibility or injectivity of the well. Further, current placement techniques for gravel packs can be a complex procedure requiring several stages and the proper functioning of moving parts in a hostile wellbore environment.
There are two methods commonly used to gravel pack in horizontal wells, an alpha-beta technique using brine as a carrier fluid and a viscous packing method using a viscous fluid as a carrier fluid. Recently, a third method was developed wherein gravel is carried using a fluid containing multimodal particle size distribution with degradable particles. In all the three methods, filling greater than 90 percent of the annular volume with gravel is difficult. In the third method, filling greater than 80 percent of the annular volume is a challenging because of the volume change that occurs when the degradable particles transform from a solid to a liquid state. Embodiments of this invention relate to a method to compensate for the volume change and also to occupy any voids that are left in the gravel pack.